A charging inlet device is installed in a vehicle such as an electric vehicle (EV) and a hybrid electric vehicle (HEV) for charging a battery mounted on the vehicle. A spring hook structure is applied to the charging inlet device to open and close a cap (refer to JP 2010-166756 A and JP H10-152071 A).
FIG. 1 illustrates a charging inlet device using a spring hook structure of a conventional example.
As illustrated in FIG. 1, charging inlet device 50 includes a connector housing 51 housing terminals (not illustrated) therein, an exterior case 52 placed to cover the circumference of the connector housing 51, and a cap 53 rotatably supported on one side of the exterior case 52.
The connector housing 51 is formed into a cylindrical shape and includes a front wall 54 blocking the front of the cylindrical shape. The front wall 54 is provided with a plurality of terminal insertion holes 55. Mating terminals (not illustrated) are inserted through the respective terminal insertion holes 55. The inserted mating terminals are then electrically connected to the terminals (not illustrated) housed in the connector housing 51.
The exterior case 52 is provided with a cap locking portion 52a. 
A packing 56 is placed on the inner surface of the cap 53. The cap 53 is arranged to be rotatable via a rotation support pin 57 between a closed position where the cap 53 is tightly attached to the front wall 54 to block the terminal insertion holes 55 and an open position (as illustrated in FIG. 1) where the cap 53 is separated from the front wall 54 to open the terminal insertion holes 55 to the outside. The cap 53 is biased by a spring hook structure toward the open position.
As illustrated in FIGS. 2 and 3, the spring hook structure of the conventional example includes a torsion coil spring 60. The torsion coil spring 60 includes a coil portion 61, and a first arm 62 and a second arm 63 extending from each side of the coil portion 61. The rotation support pin 57 is inserted in the coil portion 61. The first arm 62 is hooked on a hook surface 58 of the exterior case 52, and the second arm 63 is hooked on a hook surface 59 of the cap 53. The torsion coil spring 60 biases the cap 53 toward the open position.
When the cap 53 is turned from the open position to the closed position against the spring force of the torsion coil spring 60, a locked portion 53a of the cap 53 is locked with the cap locking portion 52a. The cap 53 is thus held in the closed position. Once the lock of the cap locking portion 52a is released, the cap 53 is rotated from the closed position to the open position due to the spring force of the torsion coil spring 60. Thus, a user is not required to open the cap 52 by hand.
In the spring hook structure of the conventional example, the torsion coil spring 60 is attached in a manner such that the rotation support pin 57 is inserted into the coil portion 61, a tip portion 62a of the first arm 62 is placed on the first hook surface 58, and a tip portion 63a of the second arm 63 is placed on the second hook surface 59. Namely, the torsion coil spring 60 is not required to be hooked on hook portions or the like for positioning the tip portions 62a and 63a of the paired arms 62 and 63, so as to facilitate the process of attaching the torsion coil spring 60.